Desalting sea water



E. R. ROTH DESALTING SEA WATER Feb. 23, 1965 4 Sheets-Sheet 1 FiledMarch 23, 1961 mnjom ...MN5 m. ambas Immun x 84%) .POI

Feb. 23, 1965 E. R. ROTH nEsALTING SEA WATER 4 Sheets-Sheet 2 FiledMarch 23, 1961 Feb. 23, 1965 E. R. ROTH DESALTING SEA WATER 4Sheets-Sheet 3 Filed March 23, 1961 Feb. 23, 1965 E. R. ROTH DESALTINGSEA WATER 4 Sheets-Sheet 4 Filed March 23, 1961 increases `the speed-ofeiciency of operation.

3,170,778 DESALTING SEA WATER Ernest R. Roth, Media, Pa., assigner toRoy F. Weston, inc., Newtown Square, Pa., a corporationv of lennsyivaniaY Filed Mar. 23, 196i, Ser. No. 97,327 fi Claims. (Cl. 62-5S) Thisinvention relates to methods and apparatus for the separation of solventand dissolved solids, as for example removal of water from an aqueoussolutionV such as sea water, and has for an object provision of a systemwhich provides economical recovery of end products comprisingessentially a solvent free of contaminants, concentrates with reducedsolvent, or separation and recovery of a purified dissolved solid.

rthough the present .invention is particularly directed to thedesaltingof sea water, it is to be understood that it may be applied to otherkinds of feed streams where the purpose is to remove solvent orcrystallized solids therefrom. v

For many years the need of Vproviding methods and apparatus fordesalting sea Water has been' recognized, and there have been manyproposals including freezing processes for accompiishingfthe statedobjective. Gne

of `the principal difculties'with desalting' systems'has `foundthat'there may be substantially eliminated the formation of minute icecrystals Whose surface area is ex-v tremely great in proportion to theirvolume, and thus there may be vastly reduced the surface area per unitWeight of ice formed in the cooling process. ln accordance with y UnitedStates Patent O 3,l7b,778 Patented Feb. 23, 1965 For further objects andadvantages of the invention and in particular for further details as tothe apparatus, heat exchange provisions, and other features of novelty,reference is to be had to the following description taken in conjunctionwith the accompanying drawings, in which:

FIG. l diagrammatically illustrates a preferred embodiment of theinvention;

FIG. 2 is a flow diagram of the system and process as a Whole;

,FIG 3 diagrammatically illustrates a modification of` the invention;

FIG. 3A is a plan view of a preferred disposition of the apparatus ofFIG. 3; f

FIG. 4 is a flo-W diagram of the system and process of 1316.3. r

In carrying out the invention in one -form thereof, the feed stream,which is-shown as sea water, enters the apparatus by a supply line 10,is elevated in pressure by a pump lll and delivered by way of a valve 12to a mixing*y line i3. The discrete seeding particles` flow by gravityfrom a bin 14 under the control of a pump 15 and by Way of a valve 16 tothe mixing line 13. The seeding particles may be pumped inasmuch aswater is Vadded to the storage bin i4 by way of a supply line 17 and avalve 18. Obviously, the water supplied to the bin lll may bea brauchline from the supply -line lil and may form a part of the feed stream ofsea water. v

VTo maintain a slurry Within tank lll, stirring means may be provided,though not shown. From the valve 16 the slurry including theseeding-particles enters the mixing line 13. There is also suppliedtothe mixing line 13 a refrigerant as from a source of supply or storagetank 19 by way of a pump 2li and a flow control valve Z1. The mixture offeed stream, seeding' particles, and refrigerant passes through apressure-reducing valve 23 which maintains constant the back pressure inline 13to assure that the refrigerant remains `as aL liquid untilafterpassage through the reducing valve 23 into delivery line the inventionthere is mixed with the feed stream discrete particles of materialsinert to all of the ingredients of the feed stream, sea water, but whichhave compositions providing surfaces to which ice readilyy forms duringthe freezing process. Byproviding'the discrete seeding particles, icepreferentially' forms about them, and inasmuch as they are provided indiscrete sizes, `as for example about a millimeter in minimum dimension,ice formsV in substantial quantity in terms of surface area relative toweight as rcompared with ice, crystals which would otherwise form in theabsence of the seeding materials ofdisf cretesize. j

ln. a preferred form of the invention, there is added y directly to themixture of seawater land seeding particles a refrigerant inert to theingredientsV of the sea water and the solids, and under such'conditionsthat the combined stream as it is fedto a freezing zone has therein asubstantial part of its volume made up of bubbles of refrigerant whichserve the function of providing increased separation rates between theseeding materials with adhering ice and residual brine. Y As themixtu-reis then fed into the freezing zone, the refrigerant in gaseous andbubble lform rises at a fast rate in the mixture, and thus'when theseeding materials have a density which makes them buoyant in the liquidmixture, the rising 'bubbles of refrigerant,

besides acting to cool the mixture, impartv added buoyancy Y Ztl.V Themixing line 24, besides being aconduit for flow of the mixture into afreezing zone 25, may be of larger diameter than pipe 13 in ordertopromote the formation of a multiplicity of bubbles of refrigerantwhich form asv l al result of the reduction `of pressure -on the liquidrefrigerant as it passes through valve 23 which also is of such designto promote bubble formation. Itis preferred that the multiplicity ofbubbles or subdivided gaseous refrigerant form in yline 24 in order toprovide increased separation rate of particles ofthe seeding material,by imparting added buoyancy to the particles in the mixture afterdelivery into'the cooling zone, and to hasten refrigeration by reason ofthe mixture of therefrigerant throughout the material to be cooled inthe freezing zone and by reason of the hashing of the refrigerant forabsorption of heat from the feed material and the seeding particles.

As a result of Vthe foregoing, the mixture as it is l delivered from theoutlet of line 24 is rapidly cooled,v and ice immediately begins to formon and about the seeding particles. Since the =through-'put is high andthus the velocities from delivery line 24 are likewise high, it ispreferred that'in the cooling-zone there be provided a turbulencedissipator 28 which may be in the form of a perforatepwall or screenhaving openingsror mesh -considerably 4larger than the seeding particlesafter addition thereto of a layer of ice. The ice thickness on theseeding particles will, of course, vary, but on average it is of nitethickness and may be of the order of 0.020 inch.

Itis preferred that the seeding materials have minimum dimensions ofabout one millimeter, and maximum dimensions not greatly exceeding threemillimeters. These t seedingmaterials are conveniently available in theform ofspheres, such for example as plastic spheres, and they,

vmay be made' of glass, synthetic plastics, metals `and wood, with thesole requirement that these beads, spheres and subdividing seedingmaterials shall be inert to the ingredients of the feed stream, seawater, inert to the refrigerant, and in particular do not provide anycontaminant in the end product of desalted water. Additionaly, theseeding material shall have a surface to which ice readily forms. Thislatter property is present for finely divided glass, finely dividedstone, particularly the silicates, aluminates, carbonates and the like,wood, the metals, and the synthetic plastics. Aside from yplastics inthe Teon and Kel-F7 class, the synthetic plastics of vof/rs both thethermosetting and thermoplastic type may be used. These materials allfall within the class of permanently solid materials at roomtemperature.

In the form of the invention illustrated in FIG. 1, it is preferred thatthe seeding material likewise have densities which in conjunction withthe presence of the gas bubbles of the refrigerant are buoyant afterformation of ice thereon. Thus, where heavier metals and glass may beutilized, it is preferred that they have hollow centers to provide theneeded buoyancy. rhe seeding particles need not have smooth surfaces; infact, a slightly roughened surface is preferred to promote formation ofthe ice with the surface.

The seeding materials will preferably be Supplied to the mixing line 24in quantity or amount roughly corresponding to about 2% to 10% by Weightof the feed stream and which will normally fall within the range ofbetween about 30% and 50% by volume of the aforesaid feed stream.

Thus as the ice forms about the seeding particles comprising at leastand as much as 5 0% by volume of the feed stream in the zone there willbe rapid rise of the particles and ice upwardly of that zone which, itwill be noted, comprises a vessel 3l having an open upper end, the wallsof which terminate in an overflow weir configuration such as thesaw-tooth configuration 31a, providing a multiplicity of weirs foroverflow of ice mush consisting of the seeding material and the adherentice. The vessel 3l is also provided with a level control 32 whichcontrols the level of brine through regulation of the operation of adischarge valve 33 for withdrawal of brine by way of line 34. f

The upper end of vessel Si is hermetically sealed into a vapor-receivinghousing 35 having an outlet line 36 through which refrigerant may beWithdrawn. Thus the vapor-receiving housing 35 provides =a separatingzonev between the refrigerant and the ice musi The ice mush, afterdischarge over the Weir 3io, flows by gravity down an inclined dischargeline 37 into a selected one of a plurality of washing Zones, only two ofwhich, the zones 33 and 39, have been illustrated. With the parts in theposition shown, a discharge opening 40a in a control valve 40, of therotating disc type and under cycle control is in register with thewashing zone 38. Thus the ice mush ows through opening 46a into washingzone 38.

It Will be assumed that during a previous cycle the washing zone 39 hasbeen filled with ice mush. Wash water supplied through a supply line 42under the control of a valve 43 is discharged from a distribution head44 for washing from the particles .of ice brine which may have adheredthereto. By reason of the fact that all particles of ice are ofsubstantial size, only a minimum of washing is required. Thus, the washwater need be only from about 3% to 10% of the desalted product.

, The wash water is discharged by way of a valve 45. At the conclusionof the washing cycle, the valve 45 is closed, and a gate valve d6 openedfor discharge Aof the washed ice into an icemelting andwater-refrigerant separation zone or vessel 427. It will be understoodthat the vessel 47 will operate ata relatively low temperature, of theorder of 34 F., and a temperature and pressure at which the refrigerant,for example butane, is liquid. Accordingly, the separation zone may beconveniently utilized for cooling and condensing the refrigerant whichenters in hot vapor form. As illustrated, it is introduced by way of aline 49 and valve 50 into vessel 47 where it is discharged in the lowerportion by a distributing lread 5l. The het refrigerant vapors risethrough the inlet to vessel t7 and upwardly through the Washing zone 39.inasmuch as ice tends to adhere to surfaces with which it cornes incontact, and inasmuch as some of the wash water may freeze in thewashing zone 39, the hot refrigerant vapor hastens the melting of theice and assures the delivery of all of the end product into the vessel47.

In accordance with the invention, a part `of the hot vapors as from aline 52, as by way of a valve 53a and line 53 into the body and valvedisc grooves of gate valve do, where it serves the dual purpose ofmaintaining all moving parts free of ice and frost, and also aids inmelting fthe ice that may remain in the washing zone 39. Alternatively,and also to supplement the previous streams of hot refrigerant vapors, athird stream may be supplied by way of a valve 54a and line 54 at one ormore points along the washing zone 39. Though the refrigerant lines havebeen illustrated in association with but the single washing zone 39, itis torbe understood that corresponding lines will be associated witheach of the other Zones and including the separating vessel andseparating zone 56.

The timing cycle is such that as the ice in washing zone 39 is fulymelted and/ or discharged into vessel 47, the washing zone 33 is filledwith ice mush. At the end of a cycle, the disc valve 4%) is rotated totransfer the fioW of ice mush to an empty washing zone 39 which at thatkvalve d5 closed. The zone 38 then becomes a washing zone withvalve 5dopen. The foregoing cycle is again repeated with closure of valve 58 andopening of delivery valve 59.

As indicated above, the temperature `and pressure in vessel t7 are suchto keep the refrigerant in liquid form. Thus there forms in theseparating zone 47 an upper level of liquid refrigerant 6? and a lowerlevel of desalted water 61. Liquid refrigerant is withdrawn by way of aline 62 and valve 63, and desalted fresh Water is withdrawn from thebottom of vessel t7 by way of a valve 64 and line 65.

Though not illustrated, the vessels 47 and S6 will be provided with huidgages for indication of the fluid interfaces. Instead of withdrawingbutane through line 62 in its illustrated position, hat line may belocated at the lower portion of the vessel and the operation willproceed as follows: The valve 6d will first be opened for withdrawaL ofthe desalted freshwater. After the interface level has been brought to apoint near the bottom of the vessel, the valve of: will be closed andthe valve 63 opened for withdrawal of the butane, together with a smallamount of water and to assure the absence of refrigerant in the endproduct, fresh water.

Since the seeding particles have in the above description been assumedto be buoyant in character, it will be understood that they will becarried substantially exclusively in the level of liquid refrigerant o@in vessels 47 and 56. Thus, the fresh water will be free of inertsolids. The liquid refrigerant may be returned to storage in the vessell? by way of line 69.

in utiiizing the system and methods of FIG. l to produce salt-freewater, meaning water having a content of salt less than about 5G() partsper million, additional features will preferably be utilized. Moreparticularly in the flow diagram of FIG. 2 there have been illustratedthe vessels, piping, pumps and circuits representative of a commercialinstallation. Sea water, preferably pretreated for the removal ofsediment and the like, is brought to the system through a supply linel0, elevated in pressure by pump lli, and through a header 72 sent individed flow through heat exchangers 73 and 74. These heat exchangersreduce the temperature of the sea water, and while under the pressure ofthe pump these streams are returned to a mixing line 13. The sea Waterthere has mixed with it a slurry iof solids -as from line 15a, Whileliquid refrigerant is introduced into line 13 by way of line 20a. Theback pressure is maintained in line 13 by the pressure regulator 23. Themixture at reduced pressure is introduced by way of line 24 into thefreezing and flotation chamber 31. From the otation chamber 31 therefrigerant is withdrawn as Vapor by way of line 36 which forms theintake to a compressor 68. The refrigerant vapor at a considerablyhigher temperature and pressure due to the compression thereof thendivides to llow by way of line 76 to an inlet of the second compressor77, it being understood that suitable flow controllers will be utilizedto assure that part of the refrigerant from compressor 68 oWS by way ofline 76 and another part by way of line 52 to form the source of supplyof the higher temperature refrigerant vapor utilized for the melting ofthe ice in the washing zone 38, as well as for utilized as a part of thedecanting operation in connection withV the vessel 47. The pump 20delivers refrigerant to the line 20a.

Wash water and brine derived from vessel 38, as well as brine from thefreezing and notation chamber 31, flow by way of line 85 to a pump S6. Aslip stream is taken from the outlet tof pump 86 for flow through lines87'and 88 through a cooling coil 89 ldisposed within Ivessel-19 toVmaintain the refrigerant below its vaporizing temperature to assure aliquid feed to thepump 20. The principal stream from pump 86 iiows byWay of line 90 to form the cooling liquid for the heat exchangers 73 and80 and is taken to waste by way of discharge line 91.

Fresh Water derived from the melting `and separating vessel47 iselevated in pressure by pump 92 and divided into two streams. A smallerfraction is returned by way of line 42 to form the source of wash waterfor the ice after delivery from the freezing chamber 31, while the majorportion liows by way of line 93 to form the cooling medium for the heatexchanger 74. The desalted or fresh water stream, after passage throughthe exchanger 74, is returned Vby way ofline 95 Vto a stripping andsolidsseparating vessel l96.

Though the vessels 47 and 56 of FIG. l have been described as of thedecanting type, it is not essential to the present invention that theseparation between seeding particlesl refrigerant, and the fresh Waterbe made in these vesse.s. A part of the seeding particles may Well liowwith the water through the lines 93 and 95 and into the vessel 96. Inthis'vessel, however, there are utilized conventional techniques forremoving therefrom all refrigerant and also removing therefrom theseeding partiduced at relatively low cost and considerably below thecost of competing processes of other kinds. The conservation of the heatrealized by the system of FIG. 2 contributes to the economy ofoperation, but basically the concept of utilizing the seeding particlesto obtain areas of predetermined size on which the ice will form appearsto be the principal contributor to economical operation in that therecovery for a given expenditure of energy is materially andsignilicantly higher, since a minimum of washing is necessary with itsconsequent loss of an end product. In addition, the discrete particlesVmaterially and significantly contribute to the speed with which the icemay be removed from the brine in the freezing and flotation chamber 31,again to increase the output per unit time of operation. These factorstogether result in a system providing economical operation to a pointWhere treatment of sea waterl to remove the salt `and dissolve solidstherein becomes practical.

Though the present invention has been described particularly inconnection with the recovery of freshwater from sea water, fit is to beunderstood that it is applicable to feed streams of all kinds invwhichsolvent or dissolvedl solids may be removed as crystalled materials bythe freezing process with direct or indirect refrigeration for thereduction of dissolvable solids and the like in the solvent, for theconcentration of the remaining product as in the case of producingconcentrates from citrus juices andthe like, or for the production ofpurified compounds removed from a liquidv component of the feed streamas crystalled solids produced by freezing and forming frozen layers onthe discretep articles and recovered by melting.

Though the embodiment as exemplified in FIGS. 1 and y. 2 operates withdiscreteparticles which with their layers of ice are buoyant in thefreezing zone, indication has already been made that the presentinvention is likewise ap-V plicable to discrete particles which areheavier than the liquid present` in the freezing zone. FIGS. 3 and 4 areexemplary of the latter system in which a freezing vessel 11i) isprovided with a normally, relatively highlevel of discrete particles asindicated at 11M. These discrete particles likewise are well above themicron range and have sizes such that their minimum dirnensionwill be atleast l millimeter, and preferably not greater than about 3 millimeters.They may be in the form of beads,'spheres,

and the like. They may be metal, and since they are not to be buoyant inthe mixture will not have hollow cores. Many of the denser rock-likematerials may be utilized, as

well as the heavier plastics.` These discrete particles may cles,whereby only water is withdrawn by way of a line 93 for delivery by apump 99 to storage and as the final endproduct of the system. Thedetails of the vessel 96 e need not here be set forth since suchseparating arrangements are well known to those skilled in the art andare available from the Dorf-Oliver Company. The refrigv erant recoveredfrom vessel 96 is returned by Way Vof a line 101 and apressure-regulatingdevice 102 to the inlet line 36 to compressor 68,while a slurry of theV seeding particles is removed by a pump 103 anddelivered by line 11M-to the storage vessel Mas a part ofthe source ofthese makeup of seeding particles which maybe required,V

likewise include wood having densities greater than the liquid mixture.l

Within the vessel 110 there is delivered through a distributing nozzle111 a feed stream Vof sea water supercooled, that is to say, at atemperature b elow its freezing temperature, and also chilled discretematerials introduced asby a star-feeder valve 113. The pressure withinvessel is low enough to assure vaporization of refrigerantcontainedvwithin the feed stream. Water freezes as ice on the discretematerials on contact of the super-cooled feed stream and chilleddiscretematerials within vessel 110. To assure lack of adhesion of iceand frost and the like as between the discrete particles and the wallsof the vessel 11),V it will be observed that these Vwalls are flaredoutwardly from top to bottom, providing a gradually in-v creasingcross-sectional area and which assures the settling and/ or flow of thefinely divided particles and their layers of ice downwardly of vessel110. At the'lower portion of the Vvessel there will be present a body ofbrine which, by means of a valve 115 operated by a liquid-levelcontroller 116, is maintained at a fairly constant height. The lower endof vessel 110 has an upwardly inclined portion 117 to form -with vessel110.a liquid trap. This air/avro assures that the refrigerant will beretained within vessel 110 and for withdrawal as by way of a line 121Bto a compressor, described in connection with FIG. 4. The eX- tension orupwardly inclined portion 117 has therein a suitable conveying meansshown as a screw-type conveyor 121 for transport of the discreteparticles together with their layers if ice. As these particles withadhering ice move upwardly above the level of the brine in portion 117,they are cleansed of adherent brine by a water wash supplied from a line122 and spray heads 123 and 124. The discrete particles and the layersof ice cleansed of brine are then deposited by the screw conveyor 121into a vertical portion of a vessel 125 provided with a liquid-levelcontroller 126 to maintain therein a predetermined level of fresh water.This vessel 125 may include ice melting means, such a hot refrigerantvapors, supplied thereto by way of a line 128. rl`he discrete particles,all heavier than water, settle downwardly of the vessel 125 and arepicked up by a conveyor shown as a screw conveyor 129 and transportedthrough the inclined section 13@ of vessel 125 and delivered to asection 131 to a vertical conveyor 132. The conveyor 132, though it maybe of any suitable form, has been shown as comprising a plurality ofmaterialcarrying blades for the lifting of the discrete particlesupwardly to an inclined feed pipe or chute 133 for supplying thediscrete particles to the star-feeder valve 113 for return to vessel111).

The hot refrigerant vapor supplied by way of line 128 from thecompressor enters into the level of liquid within vessel 12S forintimate heat exchange therewith, the ice being melted and therefrigerant being condensed. The refrigerant and water are removedthrough the operation of the liquid-level controller 126 and deliveredtogether by way of line 138 to a separating vessel 139. Fresh Water iswithdrawn as an end product from a discharge line 141B, while liquidrefrigerant is removed by a discharge line 141 to a receiving vessel142. The liquid refrigerant is picked up by a pump 143 and a substantialfraction of it delivered by a line 144 for mixture with sea watersupplied to the system by a supply line 145.

The remainder of the refrigerant is delivered byV way of line 146 to apressure-reducingv head 147 for hashing of the refrigerant within thevertical vessel 148 containing the lift-conveyor 132, with therefrigerant Vapor flowing by way of lines 133 and 13d to a compressor.'lt is in this manner that the discrete particles are super-cooled, i.e.,chilled to below the freezing temperatureof the water and thus enter thevessel 110 at a temperature to assist in the formation of ice from thefeed stream.

In order to minimize and prevent formation of ice prior to contact withthe discrete inert particles and to promote controlled super-cooling, apump 150 is supplied with brine from the liquid-level controller valve115, and a part of the brine is recirculated by way of valve 151, thatrecirculated portion entering the line 144 for mixture with the incomingsea water feed and the refrigerant is such that the initial freezingtemperature ofthe mixture of feed and recirculated brine is only a fewdegrees different from the temperature maintained in vessel 110,thus'assuring controlled super-cooling. 'Ihe remainder of the brinepasses by way of valve v152 to a pipe 153 and thence to waste, or tostorage when the system is utilized for concentration of citrus fruitjuices and the like.

As in the preceding embodiment of the invention, the discrete, sinkableparticles in vessel 11) will be present in amount corresponding withbetween A30% to 50% by Volume of the stream of sea water. By enlargingthe vessel 11d or by increasing the speed of operation of motors 169 and161 and the speed of operation of the conveyor 132, particles in sizesgreatly exceeding about 3 millimeters may be utilized, the necessarysurface area for a given production of adhering ice being provided inthis manner. Y

For ease in description, the arrangement of FIG. 3

CII

has been shown diagrammatieally and not as in an actual install-ation.As best shown in FIG. 3A, vessel 125 will preferably be located directlybehind the vessel 1513 and the receiving vessel 119 will be located infront of vessel 125, this disposition of the apparatus requiring muchless floor space and a minimum of length for the delivery chute 133.

In FIG. 4, the same parts have been designated by the same referencecharacters as in PIG. 3. For example, it will be seen that the feedstream enters by way of line 145, is elevated in pressure by a pump 165,is sent in divided flow through heat exchangers 166 and 167, in singleflow in line 141i, is joined by streams of refrigerant supplied theretoby way of a line 144s in flow connection through lines 169 and 17@respectively receiving refrigerant from pumps 143 and 172 in ilowconnection with refrigerant supply vessels 142 and 173. The line 144receives the recycled brine by way of valve 151 from pump 151Dflow-connected to the passage 117. The combined mixture enters thefreezing vessel 119, with refrigerant withdrawn therefrom being suppliedto a compressor 189. Refrigerant delivered from compressor 186 isdivided in flow, a part going to a second compressor 181 and theremaining part by way of a line 128 to form the supply of hotrefrigerant vapor to the vessel 125. The vessel in FlG. 4 schematicallyincludes the separating vessel 139 of FIG. 3 and has been so shown tosimplify the illustration of withdrawal of refrigerant by way of line141 to the refrigerant receiver 142 and the withdrawal of purified freshwater by way of line 141B to a pump 187. The' cold fresh water isutilized in heat exchange, flowing by way of line 13? to heat exchanger167 and by way of a line 13910 a refrigerant stripper 131) which, formost applications, will be a desirable piece of apparatus to include inthe system. FromV the refrigerant stripper, the refrigerant-free freshwater is' delivered by a pump 131 to storage or to further treatmentwhere that is indicated for purposes of chlorinization and the like. Apart of the fresh water stream from pump 187 is returned by a line 122to form the source of wash water for the ice within the inclined portion117 ofthe vessel 11i).

As in the embodiment of FIGS. 1 and 2, a slip stream from pump 15@ ofthe cold brine from inclined Vessel 117 is circulated by lines 1% and191 through a cooling coil 192 in vessel 142 to maintain the liquidrefrigerant `below its vaporization temperature. The waste brine flowingthrough the valve 152 passes 4through the heat exchanger 166 Ito coolthe incoming feed water and then passes through a further heat exchanger153 to cool and condense hot refrigerant `flowing through line 1% fromthe compressor 1&1 and to the refrigerant receiver 173. Where thecooling for the waste brine is inadequate to liquefy lthe refrigerant,additional cooling water will be supplied to the heat exchanger 193 asby way of -a supply line196.

In the embodiment of FlG. 4, it will be noted that a compressor 19d isprovided to receive refrigerant from the line 134 in flow connectionwith the inclined chute 133 (see particularly FIG. 3), This refrigerantwhich 'was utilized to super-cool the discrete particles enroute to thevessel 116 is compressed and flows from compressor 19S to form a part ofthe inlet stream to the compressor 130.

As previously described, the refrigerant used in the methods andapparatus of FGS. l-4 is selected to be inert to the ingredients of thesea water and the discrete particles. The temperatures and pressuresused in the different stages of operation will be dependent upon therefrigerant selected and the nature of the feed stream. Any standardreference may be used in this selection of temperatures and pressures,such, for example, as The Refrigeration Data Book, volume I, andRefrigerating Principles and Machinery, published by the AmericanSociety of Refrigeration Engineers.

It is to be understood that the foregoing embodiments of the inventionare to be taken as illustrative of the manner in which the methods ofthe present invention may be practiced and further illustrative of thetypical apparatus fcrrningembodiments of the present invention.

Features of one modication may be utilized in the other, and apparatusof didering character may be utilized in place of some of the elementsschematically iliustrated. lt is intended by the claims appended hereto-to set forth the true scope of the present invention and theequivalents thereof.

What is claimed is:

l. The method of separating from -a liquid feed stream vtwo componentsone comprising a solvent and the other `solids dissolved in Saidsolvent, the freezing temperature 'particles of a material permanentlysolid at room ternerature and' presenting surfaces to which one of saidcomponents of said mixture will .adhere when frozen, superacooling saidsolid particles prior to their delivery to said freezing zone,concurrently supplying to said freezing zone said mixture at itstemperature'below the 'freezing tempera-ture of said feedstream toinducc'rapid,

freezing on said particles of said one component, removing from saidfreezing zone to a washing'zone said particles together with saidfrozencomponent, washing adherent liquid from said frozen component,withdrawing `from said freezing zone a part of said unfrozen mixture assaid recycle'stream, and withdrawing said frozen component from saidWashing zone and returning said solid particles to their region ofsuper-cooling.

comprising withdrawing heat from said feed stream to lower 'itstemperature,

2. The method of desalting a feed stream of sea water,

adding to said feed stream a low-temperature recycle" stream havingdissolved sal-t presentin materially higher concentration than in saidfeed stream to lower the freezing temperature of said' feed'stream,

adding to said Vmixture of said feed` stream and said'VA below thefreezing temperature of said feed stream,

concurrently supplying to said freezing zone` said mixture at itstemperature below they freezing temperature of said feed stream toinduce rapidv freezing on said particles of said ice,

removing from said freezing zone to a xwashing zoneV said particlesktogether with .ice adherentA thereto, washing adherent liquid from`said ice, withdrawing from said freezing zone a part of the unfrozenmixture asV said recycle stream, withdrawing said ieeffrom said washingzone, and i returning said solid particies to-their region of cooling.3. The method of desalting a feed stream of sea water which comprises,

withdrawing heat yfrom said feed stream to lower its temperature, vsupplying to said feed stream a seed-slurry of tinely divided discreteparticles of material permanently solid at room temperature andpresenting surfaces to which ice will adhere,

adding under pressure to said feed stneam a liquefied refrigerant ofcomposition inert to said feed stream and'to said particles,

reducing said pressure for expansion of said refrigerant thereafterdelivering said mixture comprising said feedy stream, said refrigerantand said seed-slurry to a freezing zone, further reducing the pressureon said mixture including said feed stream for further expansion of saidrefrigerant for rapid cooling vin said freezing zone of said feed streamand of said particles and for increasing the production within saidfreezing zone of a multiplicity of ybubbles which hasten the freezing ofsaid ice on said particles, i' A removing from said freezing zone to awashing zone said particles together with ice adherent thereto, washingadherent liquid from said ice, `withdrawing said ice from said washingzone,

supplying to aV melting zone refrigerant vapors at elevated temperatureto said washed ice particles to melt said ice, v V withdrawing from saidmelting zone said refrigerant for further cooling-5,' Y

slurry to said feed stream,

withdrawing from said freezing zone a'stream whose v to the buoyancy ofsaid discrete partie-les with their adherent llayersV of ice. y

i References Cited by the Examiner i UNTED STATES PATENTS 2,579,42112/51 `tagan 62-58- 2,764,488 9/56 lattery j 62-123 V2,821,304 1/,58Zarchin 62-58 2,896,419 7/59 Thompson f 62-58` 2,997,356` 8/61 Pike62-58 3,017,752 1/62 Findlay 62-58 3,070,969 1/63 Ashley 62-58 f uFOREIGN PATENTS 70,50716/46 Norway. 217,766 10/,58 Australia.

841,374 7/ 60 Great Britain.

NORMAN YUDKOFF, Pi'mary'Examncr.

vROBERT A. OLEARY, Examiner.

returning said solid particles in the form4 of said seed- Y Svanoej r62-58

3. THE METHOD OF DESALTING A FEED STREAM OF SEA WATER WHICH COMPRISES,WITHDRAWING HEAT FROM SAID FEED STREAM TO LOWER ITS TEMPERATURE,SUPPLYING TO SAID FEED STREAM A SEED-SLURRY OF FINELY DIVIDED DISCRETEPARTICLES OF MATERIAL PRMANENTLY SOLID AT ROOM TEMPERATURE ANDPRESENTING SURFACES TO WHICH ICE WILL ADHERE, ADDING UNDER PRESSURE TOSAID FEED STREAM A LIQUEFIED REFRIGERANT OF COMPOSITION INERT TO SAIDFEED STREAM AND TO SAID PARTICLES, REDUCING SAID PRESSURE FOR EXPANSIONOF SAID REFRIGERANT TO INDUCE BUBBLE FORMATION AND TO SUPER-COOL THEMIXTURE BY BRINGING THE TEMPERATURE OF SAID MIXTURE BELOW THE FREEZINGTEMPERATURE OF SAID FEED STREAM, THEREAFTER DELIVERING SAID MIXTURECOMPRISING SAID FEED STREAM, SAID REFRIGERANT AND SAID SEED-SLURRY TO AFREEZING ZONE, FURTHER REDUCING THE PRESSURE ON SAID MIXTURE INCLUDINGSAID FEED STREAM FOR FURTHER EXPANSION OF SAID REFRIGERANT FOR RAPIDCOOLING IN SAID FREEZING ZONE OF SAID FEED STREAM AND OF SAID PARTICLESAND FOR INCREASING THE PRODUCTION, WITHIN SAID FREEZING ZONE OF AMULTIPLICITY OF BUBBLES WHICH HASTEN THE FREEZING OF SAID ICE ON SAIDPARTICLES, REMOVING FROM SAID FREEZING ZONE TO A WASHING ZONE SAIDPARTICLES TOGETHER WITH ICE ADHERENT THERETO, WASHING ADHERENT LIQUIDFROM SAID ICE, WITHDRAWING SAID ICE FROM SAID WASHING ZONE, SUPPLYING TOA MELTING ZONE REFRIGERANT VAPORS AT ELEVATED TEMPERATURE TO SAID WASHEDICE PARTICLES TO MELT SAID ICE, WITHDRAWING FROM SAID MELTING ZONE SAIDREFRIGERANT FOR FURTHER COOLING, RETURNING SAID SOLID PARTICLES IN THEFORM OF SAID SEEDSLURRY TO SAID FEED STREAM, WITHDRAWING FROM SAIDFREEZING ZONE A STREAM WHOSE SALT CONCENTRATION IS MATERIALLY HIGHERTHAN THAT OF SAID FEED STREAM, AND UTILIZING SAID WITHDRAWN STREAM FORWITHDRAWING SAID HEAT FROM SAID FEED STREAM.